Peter Muhlenberg did not look like this.
Portraits from life or personal knowledge
“To create portraits from life of the people depicted in this and other paintings," the Capitol architect's website says, "Trumbull traveled extensively. He obtained sittings with numerous individuals in Paris (including French officers at Thomas Jefferson’s house) and in New York. In 1791 he was at Yorktown and sketched the site of the British surrender. He continued to work on the small painting during the following years but did not [immediately] complete it; nevertheless, in January 1817 he showed it and other works in Washington, D.C., and was given a commission to create four monumental history paintings for the Capitol. Surrender of Lord Cornwallis was the second of these large paintings that he completed. He exhibited it in New York City, Boston, and Baltimore before delivering it to the United States Capitol in late 1820. He completed the small painting around 1828; it is now part of the collection of the Yale University Art Gallery.”
The 1889 statue by Blanche Nevin in the U.S. Capitol is a work of the artist's imagination.
A miniature portrait of the general from about 1784 also survives in a private collection. Here, he is facing the viewer directly and noticeably younger than he appears in the other paintings.
The images were painted at different times and depict him at different ages, but at least one feature shows they are clearly the same man. The three-quarters portrait shows he has a long nose, slightly angled eyes, and jowly cheeks. The Yorktown paintings show a side view and reveal a large and birdlike nose. Even the miniature, which might most easily have disguised the size of his nose, reveals its prominence.